


Tetrachromacy

by orphan_account



Category: Sherlock (TV)
Genre: Gen
Language: English
Status: Completed
Published: 2011-06-24
Updated: 2011-06-24
Packaged: 2017-10-20 17:03:29
Rating: Mature
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 3,949
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/215032
Author URL: https://archiveofourown.org/users/orphan_account/pseuds/orphan_account
Summary: <blockquote class="userstuff">
              <p>John knows there are animals—insects and deep sea creatures—who see things the rest of the world doesn’t.  Their eyes are attuned to a wavelength beyond the visible spectrum.  Sometimes, when he tries to visualize it, that’s how he thinks things must look to Sherlock—light, streams of data, open doors no one else can see.</p>
            </blockquote>





	Tetrachromacy

**Author's Note:**

  * For [podfic_lover](https://archiveofourown.org/users/podfic_lover/gifts).



John is so tired it feels like he’s floating.

He doesn’t mind the graveyard shift, really, considering the odd hours he’s kept since moving into Baker Street, but it had been one crisis after another, all night long. The flu has hit London in full force, and right now he thinks he’d rather jump in front of a train than see one more coughing, runny-eyed child.

Sherlock is asleep on the sofa, raggedy blue afghan piled around his legs like an afterthought, phone resting on his chest, right above his heart.

There’s been a lot of shouting recently about mobile phones causing cancer. John doesn’t actually _believe_ it—no one in the medical world really does, and he regularly keeps his in his breast pocket—but his sleep-deprived brain is conjuring up images of tumors taking root in Sherlock’s lungs, dark and cold and inevitable. Before he can help it, he’s across the parlor and reaching for the phone, picking it up off Sherlock’s chest.

Sherlock’s eyes snap open a second before the phone chirps out an alert, vibrating in John’s hand. It’s light enough in the parlor that John can see his eyes straining to focus, pupils dilating wide and dark. Sherlock is a deep sleeper; rolling him off the sofa onto the floor shouldn’t have been enough to wake him, let alone picking a phone up off his chest.

But there’s that spider’s thread of awareness, that tiny bit of the world John knows only Sherlock can see. Potential work is like a fly twitching at the edge of the web.

Sherlock’s mouth turns up at the corners. “I’ll take that.”

John slaps the phone into his palm and despairs of getting any rest that night.

 

He falls into a doze twice in the taxi, Sherlock prodding him with his elbow every time he starts to nod off. John knows better than to ask if they can stop for a coffee.

 

The light in the lounge is watery grey, not yet bright enough to make out color, but enough for John not to go stumbling over the overturned chair in the doorway. The shades are pulled for the night, the rest of the chairs pushed into the spindly table.

They’re in a university somewhere—John hadn’t caught the name. It smells like stale coffee and dust, bookshelves full of old textbooks and periodicals no one will ever read.

The dead man is lying on his back, arms held stiffly to his side, but not stiffly enough for him to have been dead for more than a couple of hours. Lestrade is talking to a medical examiner when they arrive who is, mercifully, not Anderson. John doesn’t think he could take the bickering this early in the morning without drawing his gun.

Sherlock strides to the center of the room, looking up at a dusty overhead light. “Why’s it dark? Why haven’t you turned on the lights?” He cuts off the medical examiner mid-sentence.

Lestrade gives the man a sympathetic twitch of the eyebrows before turning to Sherlock. “The light’s aren’t working. Blown breaker, I expect. We’re trying to track down a workman.”

John squints down at the dead man. It’s barely light enough to tell how old he is, let alone how he’d died. “Can we get a torch, at least?”

Lestrade has the grace to look sheepish.

Sherlock makes a noise of irritation, pulling out his mobile and handing it to John. He flips it open.

“You want me to…”

“Closer.”

John holds the phone above the corpse, lighting Sherlock’s face blue as he leans in. He looks gaunt, almost skeletal.

Sherlock tips the man’s head to the side. “Cause of death: strangulation.”

Lestrade steps closer. “That’s what I figured.”

Sherlock’s expression goes decidedly sardonic. “Really.” John bites down on his grin. “Who found him?”

“Professor, coming in early. We’re taking his statement right now. The way he tells it he heard the microwave from out in the hall—came in to see if anyone was here.”

Sherlock’s gaze goes distant. “Microwave,” he says under his breath. The light on the mobile goes dim. John closes it and opens it again, the eerie blue light flaring back.

“Got anything?” Lestrade asks. He’s hovering—he usually doesn’t do that. He’s gotten tired of Sherlock kicking him out.

Sherlock stands up. “Oh, this and that.”

Lestrade rolls his eyes. “Go on, then.”

Sherlock takes his gloves off with a practiced snap. “The killer used their bare hands. The finger marks are small, so a woman or a small man.”

Lestrade’s eyes flick to John for a moment, as if he expects him to be offended—like he speaks for all small men everywhere—before settling back on Sherlock. “Would a woman be able to do this?”

Sherlock cocks his head. “Doctor?”

John is just about to alert the BBC—Sherlock has actually asked a Yard medical examiner for his opinion—before he realizes which doctor he’s referring to.

“Er…” John clears his throat. “With the right pressure, in the right place. It’s definitely possible.”

“So I’m looking for a woman or a small man. That’s more than half of London.”

“Patience, Inspector.” Sherlock gestures down at the man. “His arms. See how they’re held at his sides. Even you lot couldn’t have managed to miss that.”

“What about his arms?”

Sherlock closes his eyes, turning his face up to the ceiling, as if begging the heavens for strength. “He’s been moved—he didn’t die like that. See the tracks in the carpet, there—.” He points, and it’s so dark in the lounge John can’t make out the _color_ of the rug, let alone any drag marks. But he’s sure Sherlock could have found them in the dead of night, wearing sunglasses.

“So he was dragged,” John prompts, because Sherlock doesn’t bring him along for his medical expertise—he brings him to play his straight man. “What does that mean?”

“It means the killer took the time to position him—look at the pose—he’s relaxed, his eyes are closed. It looks like he’s sleeping.”

“What—.”

“And the marks on his neck. He was choked from the front.” He reaches for John, hands splaying across his throat in demonstration. In the dark his eyes are colorless, face pale enough to be a ghost’s. His hands are shockingly cold, and John half-expects them to tighten down. Braces himself for it. “That suggests a personal connection. You don’t choke someone with your bare hands, face-to-face, unless you know them very, very well.” He steps back, mouth twitching up into a grin.

John rubs lightly at his neck. It’s good to know Sherlock likes him well enough to choke him to death.

“Look for an angry girlfriend or boyfriend, perhaps someone with some medical knowledge. They weren’t in this department, whatever it is.”

It sounds like guessing, but John knows better by now.

“How could you _possibly_ know that?” Lestrade should know better by now as well.

Sherlock’s lips curl up at the edges. “Well, if they spent any time here, they’d know that using the microwave while the heater is switched on will blow a fuse. I expect they used the noise to cover up the sound of the murder. I wouldn’t be surprised if they turned on the faucet as well.”

John knows there are animals—insects and deep sea creatures—who see things the rest of the world doesn’t. Their eyes are attuned to a wavelength beyond the visible spectrum. Sometimes, when he tries to visualize it, that’s how he thinks things must look to Sherlock—light, streams of data, open doors no one else can see.

But, every so often, John feels like he catches a glimpse.

“Sherlock—,” John starts, as they head for the door.

“Yes, I know. A small man.”

“Do you think it’s him?”

Sherlock glances back for one last look at the dead man on the carpet. “He wouldn’t do it himself. Besides, it’s too simple. I have no more reason to expect him than I have to suspect you.”

“Yes,” John allows, when they’re back out on the curb. The fog has turned into a fine, misting rain, soaking into his hair, turning the concrete slippery. “Except that he’s a criminal mastermind, and I’m not.”

 

John gets around two and a quarter hours of uninterrupted sleep when he’s awoken by a rhythmic thumping, short and staccato, like metal on wood.

He finds Sherlock pacing across the parlor floor with an old fashioned, silver-tipped cane, slamming it down with every step. His laptop is open on the desk, John’s on the coffee table, just in case inspiration strikes when he’s on that side of the room. The curtains are open just wide enough to let in a stripe of grey sunlight. John knows without asking that he hasn’t slept and that he won’t sleep again until after the case is solved, the murderer dead or behind bars. John may be able to bully or bribe him into eating a bit of toast, but nothing else will pass his lips until they’re installed in the corner of some dingy late-night Chinese.

After a day or so without sleeping and maybe half of one without eating, and John tends to be absolutely useless. It hasn’t always been like that—back in his unit he had gone for days without sleeping, exhaustion tugging at his eyelids, vision spotting grey round the edges, sorting out what seemed like injury after injury, corpse after corpse.

Maybe it’s his reverse PTSD. Or maybe he’s just getting old.

John is half-convinced Sherlock draws his energy from some other source—soaks it in through sunlight, or perhaps from the air around him, since he can spend days on end with the curtains drawn, sulking in the dark.

John yawns widely. “Anything yet?”

Sherlock looks up sharply, like he’s only just realized John is there, though that certainly isn’t true. He most likely knew it the moment his feet touched the carpet.

“Yes,” he says, glancing over his shoulder and making a grab for a piece of notepaper on the coffee table. “I need you to go to this address. I had reason to believe the murderer is a dancer, and now I’m sure of it. I need you to go to her dead boyfriend’s house and then to the Royal London Theatre—.”

“Let me see.” John takes the page. It’s scribbled all over with writing, names and dates, words crossed out and then rewritten, lines and arrows connecting them, above what appears to be a hastily drawn family tree.

Sherlock hovers over John’s shoulder as he looks the paper over, impatience radiating off him in waves.

“Alright, I’m going. I expect tea when I get back.”

That barely gets a grin, but as John heads for the stairs he hears, “I’ll tell Mrs. Hudson.”

 

John finds Jennifer Harvent’s body in much the same fashion as her ex-boyfriend’s, lying face-up on her dressing room floor, costume ripped down the front, red lace frothing up like blood, sequins glittering in the soft light.

John is reaching for his mobile to let Sherlock know that he might as well come up with a new suspect, when he feels something flexible and thin wrap around his neck.

He sputters, hands going to his throat, fighting. Trying to pull away only tightens the cord, but he can’t seem to stop struggling, even though the part of his brain that is still a doctor knows his windpipe could be crushed.

Someone speaks, whispers beside his ear, but he can’t hear it over the sound of his own panic.

As John’s vision begins to spot he can’t help wondering if Sherlock will find a new medical examiner when he’s dead—if he’ll know it’s happened, see it come up in that world of distant color that only he can see.

When John swims back into groggy consciousness he is freezing and his head feels like it has shrunk, become too small to hold his brain. He coughs, sending agony ripping through his throat, and when he tries to move it’s to find that, for the second time since he’s made Sherlock’s acquaintance, he’s tied to a chair.

He lifts his head again, slower this time, blinking, trying to clear his vision long enough to see where he is. He needn’t have bothered—there’s nothing to see but a blank wall, and it’s so dark he can barely make that out.

“Sorry, John,” a voice says from somewhere behind him, high and mocking and utterly familiar. “Swing and miss, I think.”

“You’re—,” John says, or tries to say. It comes out choked and rasping, sending him into another fit of coughing.

Jim Moriarty steps into his line of sight, dressed in a dark suit that’s probably worth twice as much as the entirety of John’s wardrobe. The look on his face is politely disinterested, like he’d just happened to find a man trussed up in the dark, and it had been the third in a week.

“Feeling a bit under the weather? I don’t blame you. I’d offer you a lozenge if I had one.” He smiles—or rather, the corner of his lips twitch upward, like a spastic tick.

“Why—.” John swallows the question back down. There is no point in asking a psychopath ‘why’. “What are you doing?” he asks instead, and the voice that comes out doesn’t sound like him at all.

“Well, while you were asleep—not that it’s any of your business—I was brainstorming how Sherlock Holmes will react when he finds his favorite toy all broken.” He turns smoothly on his heel, making his way back up the room. “Or, maybe I’ll make him think that you were the one strangling all those poor souls. Because I could do it, John. I really, really could.”

John doesn’t disagree, so he doesn’t say anything. His throat hurts too much, and besides, he doesn’t think begging for mercy is going to do much good.

“Maybe I’ll set a cunning trap for him,” Moriarty muses. “I think you’d be excellent bait. I could drape you with explosives again, though it does seem a shame to cover up that lovely figure.” The smile is back. “Maybe I’ll just tie you up and leave you on a railroad track—that’s appropriately dramatic, isn’t it?”

John heaves a laugh that turns into a cough halfway through. “Blowing up old ladies not enough for you anymore?”

Moriarty looks at him for a few seconds, expression blank, like the mechanism turning the gears in is head has broken down. A moment later he plants both hands on the arms of John’s chair, leaning in close enough to tell he’s been chewing peppermint gum.

“That’s never been enough for me, John, you know that.” Moriarty brushes his hair back out of his eyes, touch almost tender. “Or you will very, very soon.”

 

John is expecting torture, but it doesn’t come. At least, not as far as he can tell. It’s just the dark and the silence, the pain in his head and the building numbness in his bound hands. At some point he thinks someone must have come in and given him water, but it could have been part of his dreams. Or his dreams may have been part of his memories, things that flicker in front of him in the dark. The war, gunfire, huddling beneath a pile of corpses for warmth in the desert night. Lying in the dirt, feeling his heartbeat steadily pushing the blood out of him through a hole in his shoulder.

Sherlock’s eyes in the blue, lucent shadows of a swimming pool, wavering and indistinct as the world explodes above them.

Sometimes Sherlock is the one with him in the dark, smelling like tea and wet wool and whatever he’s used recently to wash his hair. Other times it’s Harry, reeking of liquor and crying, tears forming at the corner of her eyes to trail down her cheeks. She doesn’t make any sound as they fall. Devon, the boy from Glasgow who John had seen reduced from a thing that walked and talked to something that didn’t even resemble a human being, machine-gun fire taking off his head, ripping open his torso.

He smiles at John, winking. “You’re well and truly fucked now, aren’t you?” he says brightly, leaning back against he stone wall.

“I don’t know,” John says. “I suppose so.”

There are times when he wakes up in bed and walks downstairs to find Sherlock drinking coffee and reading the paper, forehead creased with the particular consternation that comes of all the recent London murders being exceptionally dull. “Good morning,” John greets him with a yawn.

“Mm.” Sherlock acknowledges him with a raised eyebrow. He raises his coffee to his mouth, glancing up before saying, “It’s odd that you’re having fantasies about me, isn’t it?”

“What?” John chuckles. “I’m not having fantasies.”

Sherlock smoothes the paper out, flipping it over. “Suit yourself.”

Something sharp jabs into John’s upper arm and he jerks out of the dream. There is a yelp close to his ear, the distant sound of something scittering across the floor followed by a string of curses.

“You’re drugging me,” John says, the next time he smells the now-familiar spice of Moriarty’s cologne.

“Me, John? It hurts me that you’d say that.” He leans in close. “It’s true, of course, but it still hurts.” Cool fingers brush his cheeks. The cologne in his nostrils is choking.

“Don’t touch me.”

 

He considers praying a few times—in his more lucid moments—but he hasn’t believed in God in a long time, can barely remember back to when he did.

Instead, he beings talking out loud, describing where he is, how he got there, everything he’s managed to pick up. He doesn’t consciously acknowledge the thought, but he knows he is talking to Sherlock. Maybe saying it aloud will push his words into that extra-sensory world that only he can see, twitch at the corner of the web.

“It’s a small room. Dark, but I think the walls are white. The floor is cement. It’s always cold. It smells like…rot, mildew maybe. I can hear water sometimes. I don’t know if it’s a faucet, or…”

He spends one hallucination with Sarah. She strokes his hair, whispering things he can’t make out, and all the while his arm aches more and more. He’s long-since lost the feeling in his hands.

 

When someone shakes him, all he can register is mild surprise.

“John.” The shaking gets rougher, the voice tight and frightened. “John!”

He blinks his eyes open, but he’s forced to close them again immediately against the glare of sunlight. Blackout curtains have been removed from were they had covered a squat, rectangular window near the ceiling. Someone who smells like tea and wet wool is standing over him.

The ropes are loosened from his arms, and John has to bite back a cry as his hands are lifted. He knows someone is touching them, but he can’t feel anything but the screaming ache of the blood rushing back.

“John, can you hear me?”

John blinks past the sunlight. “…Sherlock?”

Something loosens in the lines of Sherlock’s forehead. He looks back, shouting over his shoulder. “Call an ambulance! Lestrade!” John winces at the noise and Sherlock’s gaze turns apologetic.

“What…” John’s voice is rusty with disuse. “What happened? Where—?”

“Basement.” Sherlock has picked up one of his hands, thumbs rubbing gently across his knuckles. “Can you feel that?”

John shakes his head. “No.” His fingers are tinged blue, but they haven’t begun to go black yet. The part of his brain that’s been through medical school and had spent years digging bullets out of people knows that means he can’t have been tied up for very long.

But that can’t be right. It feels like his entire life has been spent in this tiny room.

Sherlock offers his arm and John takes hold of it, legs shaking as Sherlock hauls him to his feet. He feels hands moving up his back and down his arms, Sherlock checking to make sure all his parts are still there.

“I’m—I’m fine,” John says, before dissolving into laughter, because he’s never said anything less true.

 

When John wakes up again he’s in a hospital bed, IV stuck in his left hand, blankets folded neatly atop his legs, the steady beep of the heart monitor uncomfortably loud. At least he won’t forget he’s alive.

“—Keep this up, Sherlock, you just can’t.”

John recognizes Lestrade’s voice, hushed as it is. “You’re going to get him killed. It’s fine to risk your own life tearing off, not waiting for backup, but he’s a _doctor_ for God’s sake—.”

“And a soldier,” Sherlock’s voice cuts in smoothly. “He’s seen far worse than this.”

John can see them now, on the other side of the thin white curtain, highlighted against it like a screen in a magic lantern show, Sherlock tall and thin with his hands in his pockets, Lestrade shorter and agitated.

“Sherlock, you aren’t—.”

“You need us.”

“I need _you_.” Lestrade isn’t bothering to whisper anymore. John can’t recall him ever losing his temper.

When Sherlock speaks again his voice is clipped and final. “ _I_ need him. We are, as they say, a packaged deal.”

John stares at the ceiling, listening to the last, tapering ends of the argument, a pair of feet retreating out of the room and up the hall.

“I assume you heard that.” Sherlock steps around the curtain. He has the morning newspaper in one hand and his scarf dangling from the other.

“Heard what?” John asks breezily, or as breezily as you can while stuck all over with needles.

Sherlock smiles briefly. The circles under his eyes are as dark as bruises and he is even paler than usual. “Are you. I mean, obviously you’re not, but I hope you’re feeling…passably well.”

“I’m—.” John has to stop and make himself actually ponder the answer. “I’m alright. At least, everything seems to be working like it should. Sherlock, was he—.”

“Gone. The house was empty.” Sherlock’s nostrils flare and his lips tighten. “It was him, then? I knew it was him. Just a feeling, but only he knows how—.” Sherlock bites off the end of his sentence, giving John a swift, dark look.

John leaves it alone, leaning back against the pillows. “Sorry for getting kidnapped. Didn’t mean to cause trouble.”

“What trouble?”

John jerks his head toward the curtain and the door.

Sherlock makes a dismissive gesture with the newspaper. “He’s fine, just upset he let a murderer get away.”

“And what about you?”

“What do you mean?”

“The murderer. He got away from you too.”

That slow grin is spreading over Sherlock’s face, turning him from wan to something you couldn’t look away from, even if you tried. “Not for long.” He gives the newspaper a shake. “There’s been another murder.”

“Could be another trap.”

“Undoubtedly.” Sherlock seizes up halfway through handing him the paper, pulling it back out of reach. “But, ah…” He coughs. “Of course I’ll wait until you’re well to tell you the details.”

John has to resist the urge to roll his eyes. He holds out a hand. “Give it here. If you think I’m going to let a week-long fugue state—.”

“Two and a half days,” Sherlock corrects.

“—Two and a half day fugue state in the nest of a psychopath ruin my enthusiasm, then you really don’t know me at all.”

Sherlock’s smile is crooked as he slaps the paper into John’s hand. “No, I suppose I don’t.”


End file.
